How much walking does a serpentine pick path save?
In our estimates, a serpentine pick path was 30 to 44% shorter than a same direction path for one full sweep through every rack in a zone. The saving grew with rack length and with the number of racks. In an 8-rack pallet zone with 27 m racks, the estimate fell from 407 m to 238 m.
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The example from our pick path clip
The pallet storage zone in the pick path clip has 8 single-sided pallet racks, each 27 m long (10 bays of 2.7 m), with 3.5 m aisles. Walking every rack face in the same direction gave an estimate of 407 m per sweep. Switching the zone to serpentine gave 238 m, 42% less.
Results across 15 layouts
Each layout has parallel single-sided racks 4.6 m apart (a 1.1 m deep rack plus a 3.5 m aisle), with bays 2.7 m wide.
| Rack length | Racks | Same direction | Serpentine | Saving |
|---|---|---|---|---|
| 13.5 m (5 bays) | 4 | 97 m | 68 m | 30% |
| 13.5 m (5 bays) | 8 | 208 m | 140 m | 33% |
| 13.5 m (5 bays) | 12 | 319 m | 213 m | 33% |
| 13.5 m (5 bays) | 16 | 430 m | 285 m | 34% |
| 13.5 m (5 bays) | 24 | 652 m | 430 m | 34% |
| 27 m (10 bays) | 4 | 190 m | 122 m | 36% |
| 27 m (10 bays) | 8 | 408 m | 248 m | 39% |
| 27 m (10 bays) | 12 | 625 m | 375 m | 40% |
| 27 m (10 bays) | 16 | 843 m | 501 m | 41% |
| 27 m (10 bays) | 24 | 1,278 m | 754 m | 41% |
| 40.5 m (15 bays) | 4 | 284 m | 176 m | 38% |
| 40.5 m (15 bays) | 8 | 609 m | 356 m | 42% |
| 40.5 m (15 bays) | 12 | 934 m | 537 m | 43% |
| 40.5 m (15 bays) | 16 | 1,259 m | 717 m | 43% |
| 40.5 m (15 bays) | 24 | 1,909 m | 1,078 m | 44% |
Serpentine was shorter in every layout. The saving grew with rack length, from 30 to 34% for 13.5 m racks to 38 to 44% for 40.5 m racks, because a same direction path walks back along every rack before starting the next one.
Method
The figures come from the route estimator Waresify shows when you generate a pick route. A sweep visits every rack in the zone once, in route order. The estimate adds the length of each rack face walked and the straight-line distance from the end of one rack to the start of the next.
- It does not route around racks, so real walking can be longer.
- It leaves out the walk to and from the pick start and drop-off points.
- It covers a full sweep. A pick round that visits only some racks saves less.
Your own layout gives its own numbers. Waresify shows the estimate for each route pattern before you save it.
Questions
What is the difference between a serpentine and a same direction pick path?
A same direction path walks every rack face the same way, so the picker walks back to the start side before each new rack. A serpentine path reverses direction on every other rack, so each rack starts where the last one ended.
Why would a warehouse use a same direction path?
It fits aisles with one-way traffic rules, and pick lists that always enter from the same side. The walking estimate shows what that rule costs in distance.
Does the saving apply to every pick round?
No. The figures are for one full sweep that visits every rack. A pick round that visits only some racks saves less, because the saving comes from not walking back along each visited rack.